Identification: Plants are one to three feet tall, smooth,
erect, and branched at the top. Leaves have toothed edges
and taper to a pointed end. Flowers are small, white, and
arranged in clusters.

Distribution: Found from Minnesota south to northern
Louisiana and east, with the exception of the Florida peninsula.

Habitat: Found in hardwoods, timber areas, woodlands, and
damp and shady pastures. It grows only in shady areas.

Control: Do not allow animals to graze this plant under any
circumstance. Fence off wooded areas, and provide
supplemental feed (especially in the late fall or during dry
conditions). Be aware that control of white snakeroot with
one application of a herbicide is rarely acceptable, and
multiple applications are usually needed. Exclusionary
fencing, mowing, and multiple herbicide applications may
be the best control options. When using a herbicide, be sure
to carefully follow all grazing restrictions and other pertinent
information stated on the herbicide label.

Toxin: Tremetol is a viscous oil extract of the white
snakeroot plant that contains a number of chemicals
including tremetone, dehydrotremetone, hydroxytremetone,
and desmethylencecalin.

When Toxic: Even though tremetol concentrations decrease
slowly as the plant dries, toxicoses have occurred after
ingestion of hay or dry plant stalks in winter. White
snakeroot is also toxic when eaten fresh.

Toxicity: Exact toxicity levels have not been reported for
horses, however, horses are generally believed to be more
susceptible to white snakeroot than ruminant livestock.
Toxicity occurs in cattle ingesting 5 to 10% of their body
weight over several days. A single dose of 5 mg/kg of body
weight of green material is reportedly toxic to Angora and
Spanish goats.

Signs and Effects of Toxicosis: Horses may die one to two
days after ingestion of the plant. They develop difficulty
swallowing, muscle trembling, and a basewide stance with
their head held close to the ground. As the disease
progresses, skeletal and heart muscle damage occurs, and
horses are unable to stand.

Treatment: Remove horses from the white snakeroot source.
Activated charcoal, followed by a cathartic, may reduce
absorption or prevent reabsorption of the tremetone.

Thanks to the following fact sheet reviewers: Ron Genrick, Assurance Feeds and Harlan Anderson, DVM.
Photos provided by Kristi Starzynski, University of Minnesota Extension and the University of Minnesota Strand Memorial Herbarium.